Zero-searching accurate positioning method based on magnetic railing ruler

The invention belongs to the technical field of control, and particularly relates to a zero-seeking accurate positioning method based on a magnetic railing ruler, the positioning method is implemented based on a focusing device, and the focusing device comprises a focusing control unit, a focusing execution mechanism, a focusing position feedback unit and a limiting feedback unit; compared with the prior art, the method has the following beneficial effects: (1) compared with a traditional cam focusing system, a linear motion focusing mechanism based on the method adopts a voice coil motor, and is simple in structure and high in response speed; and the zero searching speed can be effectively ensured. And (2) compared with a traditional cam focusing system, the linear motion focusing mechanism based on the method adopts a magnetic railing ruler and an incremental encoder as position feedback devices to replace a traditional position potentiometer and an analog-to-digital conversion measurement system, and the m